This thesis describes the investigations carried out into the crashworthiness of side impact beams. Two specific beams were investigated: a commercially used steel beam and a prospective composite beam made from a glass fibre weave within a polypropylene matrix. The components were simply supported and were subjected to quasi-static and impact loading, the latter experiments being performed using a Drop Weight Test (DWT) rig. Static and dynamic Finite Element Analysis (FEA) was used to model the behaviour observed during testing. Ansys v5.4 was used for the static FEA while LS-Dyna3D v940 was used for the dynamic FEA. The objectives of the project were to assess and then model the behaviour of the steel and composite side impact beams. This behaviour is in terms of both the beams' static and impact response. The beams were tested to determine their elastic behaviour, when and how failure occurs and their post-failure response. Important factors in their performance were identified. The modelling offered insights into the beams' behaviour and could potentially be used as a predictive tool in design activity. It was found that, for the loading conditions and material type used, both the static and dynamic FEA could provide accurate predictions of the behaviour of the beams although both types of FEA had their limitations.